Twins of a Sort
by Autistic Writer
Summary: When Kevin's sister comes to Bellwood for a quick visit, Ben falls in love with her. However, will their happiness last with the arrival of the Forever Knights. Read and find out.
1. Chapter 1

**Hello, this is yet another challenge by Black-Tortoise-of-the North. I hope to impress everyone with yet another Ben 10 story. I found this idea to be interesting and I hope fans of the show will enjoy it. Well, here's the first chapter. The story takes place during Ultimate Alien. I love that show than the newer one. Why did they change the animation of Ultimate Alien? WHY!**

Disclaimer: I don't own Ben 10.

_Chapter 1: Kevin's sister? _

There were many things Kevin Levin didn't want his friends to know about him. It is because he held secrets from them that he would block them out of his life at times. Yet, one of those secrets was trying to let itself out through a text message.

Kevin had been texting someone through the ride back from visiting Ben and Gwen's Grandpa Max. Ben was growing curious of whose Kevin mystery texter was. Ben wasn't able to see who it was because he was driving the car with Kevin at the passengers seat and Gwen in the backseat. Although, Gwen wanted to respect Kevin's privacy; she couldn't help feel a little jealous of who ever Kevin was texting.

"So, are we going to get any clue as to who you are texting" Ben grumped as he wanted to know who he was texting

"Nope, not telling you" Kevin said focusing on his phone

"AHHHHH come on" Ben was complaining like a 5 year old boy, who didn't get what he wanted.

"Ben, if Kevin wants to tell us who this person is, then he will tell us" Gwen said "Even if it's a girl"

Even though Kevin knew Gwen was ok with him texting other people, he couldn't help but feel a stinging glare from her as if he disrupted some sort of balance in her system of her life.

"Besides, it wouldn't matter anyways" he shut his phone as he relaxed in the seat of Ben's car.

However, their social life would be cut short by explosion that happened within a bank.

"Well its hero time" Ben called out running out of the car.

Gwen looked at Kevin giving him the 'we are not done with this conversation' face.

"You guys done fighting, there are Forever Knights to fight" Ben looked at them with Gwen and Kevin following close behind him.

Inside the bank, the Forever Knights were stealing gold from the vault of Bellwood Bank.

"More gold for our king" one of them spoke out

Ben and the gang arrived as the knights spotted them

"Why can't you guys steal gold some other night? I have a math test tomorrow" Ben told them.

Uncaring about his education, the Forever Knight charged at Ben and his friends with plasma guns and swords.

This didn't take long for Ben to turn into Four Arms. Kevin rush to where the gold was and absorb its properties to become solid gold in order to fight them. Gwen just simply blasted them with her mana.

The fight raged on for what looked like an hour. Most of the Forever Knight were either down for the count or tied up by the trio. One of the knights had fled from the battle. Kevin looked at Ben and Gwen who had nodded for Kevin to chase after him.

Kevin was rushing into the alley that the guy escaped to. He looked everywhere for where the knight was.

"Come on out you coward" Kevin looked around as the knight was behind him.

However, Kevin turned back long enough to see the knight knocked out by a steel arm that extended itself long enough to hit him.

Kevin sighed as he looked around knowing whose hand that belonged to.

"Nice to see you again, Kevin" the voice smirked

"Kari, come on out" Kevin looked around to see where she was

"O come on you know me so well. You even know my favorite game, hide and go…ahhhhhh" Kari said before Kevin deduced where she was and pulled her from it.

"Kari, what are you doing here?" Kevin growled looking at her

"You weren't answering back to my texts, so I decided to investigate where you were" Kari smirked

"Kevin" Ben and Gwen went to find him as he looked at her.

Without a second thought, Kevin pushed her towards some trash cans in order for him to hide her.

"Hey, you got him" Ben told Kevin

"You alright" Gwen questioned him

"Yea, I am alright, why wouldn't I be alright" Kevin chuckled "I think we should go home"

"O come on, going out to fight bad guys was your idea" Ben crossed his arms "Why suddenly do you want to go home"

"O it's none of your business Tennyson" Kevin growled before a voice appeared behind him.

"Ow, that really hurt my head" the woman got up.

Ben and Gwen saw a woman with jet black hair that extended down to her waist. Her eyes were covered by the hair as her mouth and nose were visible. Her jeans and dark hoodle looked similar to Kevin's outfit.

"Umm, Kevin who is this" Gwen called out seeing a girl behind him

"It's no one" Kevin tried to avoid the subject

"You must be Gwen and Ben Tennyson. My brother has told me so much about you two" She said shaking their hands and giving them a sly smile.

"Sister, you have a sister" Ben and Gwen were shocked at Kevin

"Yea, this is Kari Levin, my sister unfortunately" Kevin said before his sister slapped him upside his head

"Yea, I guess we will be seeing more of each other" Kari smiled "See you at home big brother" Kari smiled more leaving Kevin to be questioned by his friends.

**I think this is a good stopping point for chapter 1. Tell me your thoughts on this chapter. Did you like it, did you dislike it? Let me know by your comments and reviews. Hope everyone has a great day. **


	2. Chapter 2 Brother and Sister chat

**Hello again, figured my first chapter was a little off, sorry about that. I just wanted to get the story in. I will try to do better. I hope not to make Kari like anyone OC, which was not my intention. So, here is chapter 2. **

**Kira Sema: Well no such luck and I hope not to mix our OCs in the future. **

_Disclaimer: I don't own Ben 10._

Chapter 2: Brother and sister chat

Kevin had parked his car in the garage. He didn't want his friends to know about his sister because he couldn't believe it himself that he had a sister. Their father had raised her until his death and she had been living alone until the day Kevin and his mother found her. His mother had told him a few years after he became friends with Ben and started to fix his life around.

He couldn't think of a good excuse to say as to why he kept his sister's existent from his two friends. Kevin started to think of reasons why not to tell Gwen.

Although, Kevin and Gwen were really close to one another to the point that Gwen got along with his mother, he couldn't exactly had a complete trust of something so simple as him having another sister. Who knows what stuff Kari would share about Kevin? He shook his head as he dived into the bathroom to change into his pajamas.

Ben wasn't exactly a person he could trust either, he would probably flirt with her while they have a friendship. It made Kevin even sick to think his tomboyish sister in love with Ben in such a way.

As he was coming out wearing sweat pants and a dark t shirt, he could tell from what little plumbers training he had, someone was in the room.

"Come on out, Kari. They aren't here" Kevin sighed

"O, poop. Here, I thought the three of you would hang out in your own room" Kari said as Kevin turned towards her as she got off his bed.

"I told you I wanted to meet you here to talk" Kevin looked at her "Not when there was danger"

"O, blah blah. I fought coyotes over food that was more successful than those medieval jerks" Kari said crossing her arms sitting in Kevin's wheelie chair.

"Does mom know you're here" Kevin questioned.

"Mom barely notices when you are gone, do you think she would care if I was here" Kari glared

Kari was far more than your average girl. Kari shared Kevin's ability only the fact that she was faster than he was, due to the fact that she had survived in the desert due to their father's training. Kevin didn't hate his sister, he just disliked the fact that his father took her along while he was stuck with his mother.

He could tell that Kari wanted Kevin's life. The relaxation, the friends, talking about relationships, school, homework, and anything else that related to be what would be a normal life. However, Kari learned from her father how to survive in harsh environments, how to dispatch bad guys, and always keeps on her towns just in case something happens to her.

Kevin could tell that Kari was thinking about spending time in Bellwood. He wanted nothing but to spend some time with his sister that he barely knows. Yet, the pressure of most things was getting to him.

"So, tell me about Gwen, you two dating" Kari said as she caught Kevin off guard with such a question

"That's none of your business" Kevin barked

"You're my brother; everything you do is my business. No matter how personal it is" Kari told her brother as she shook her head.

"Well, you don't need to know about my relationship with Gwen" Kevin glared at her

"Hey, hey calm down I just wanted to ask you about that, sheesh" Kari said pulling up her hands in protest. "I can't believe you were hanging around with the legendary Tennyson family"

"It's not something I enjoy at times, but they are alright" Kevin looked at her

"She's the only reason you are even friends with that family. If it wasn't for her, you would probably go destroy the world with the powers of the Omnitrix" Kari looked at Kevin

"Wait, how did you…" Kevin stood up looking at Kari

"The news doesn't keep me updated on you for nothing" Kari replied just as fast as he asked it.

"So, how long are you staying" Kevin looked at his sister wondering how long was she really staying.

"Maybe I will stay for a few weeks, a few months; having really decided yet though. Why, ready to kick me out just because. Seems rather cold hearted of you" Kari fake gasped at such a thing until she bursts out unable to contain her laughter.

Kevin looked at his sister as he shook his head. He knew his sister wanted to stay here. He wanted to give her a normal life as well.

"Fine, but just be careful, I don't think I could live with myself if anything were to happen to you"

"Gees, stop worrying so much Kevin. I am not a four year old. I can take care of myself" Kari crossed her arms as she got up

"Well, I don't want you to get hurt, sometimes you just remind me of" Kevin was about to say Ben's name as he and his sister was so alike. They both annoyed him to an extent. They both ate the similar food. Kevin could even tell when they both were lying to him or Gwen in front of Kevin. They were also both stubborn when it came to listening to him.

"Who do I remind you of, that boy with the watch" Kari looked at him

"Yes, Ben" Kevin looked up at her

"I don't know, I think he was kind of cute" Kari smirked before busting into laughter. "I am just messing with you bro. There is no way I am going to fall for that geeky guy. Besides he is not even my type. The celebrities that are so full of themselves that they could take on the world"

"Good, the last thing I need is more things to make me barf" Kevin looked at his sister changing into her pajamas seeing her large bag on the floor and out she came with a sleeping bag and looks over at her brother.

"Kevin, does it get any easier, you know being a normal kid" Kari looked at her brother

"Kari, nothing is ever normal in this world. We live in a galaxy that is probably willing to invade us right now while we are not looking" Kevin gave a little yawn as he relaxes on the bed.

"Yea, I guess you are right there" Kari nodded.

Kevin had drifted asleep as his sister had tucked him in and allowed him to sleep as she was the only being awake in the house. She had looked at her eyes being hidden by her hair as times had caused her to crash into things. She has gotten use to the things that she crashes into. She stares around Kevin's room wondering what kind of items Kevin has locked away.

She found a secret photo album on his desk detailing the events of her brother's past. Kari had seen him in the news when he rampage the Tennyson family as he blamed Ben for his first transformation.

She giggled as she kept on looking at the photo album, wanting what he had, what a life. Kari looked through every page as it had everything she could ever want in a normal life: Going on adventure, sharing memories, having friends to hang around with and being there for those loved ones.

She didn't realize that a tear ran down her face as she felt jealousy that her brother experienced what she want. Though, she couldn't argue with what Kevin was jealous of. She knew their father better than he did. She looks at her brother almost waking up as she quickly hid the book and smiles at her older brother.

She was about to go to sleep, but she saw Kevin's keys outside the bedroom and smirked. When would she ever get a chance of driving his car? An evil smirk rested upon Kari's face and sneaked off in a fast of lightning to grab his keys and drive his car.

With that Kari was off in her brother's car. She felt such a rush as she had arrived in her small motorcycle. To compare, her brother's car felt just as fast. She disliked the fact that Kevin loved his car more than his 'girl'. Kari shook her head.

Upon approaching a street, a group of hormonal teens were in another car. Kari tried to ignore the guys thinking of them as a waste of her time. They threw soda cans and were egging her on. Kari breathing in.

"Come on Kari, they are just daring you to go faster. Remember what dad said. Boys are just idiots and will do anything to get on your nerves" Kari breathed in and out making sure her anger didn't get the better of her.

"Come on you wimp" One of the boys shouted

She growled as she wasn't a wimp. She hated to be called a wimp. She dared to prove them wrong with one push of the pedal. She made the losers eat their words as she had zoomed off way beyond them.

She cheered as she started to laugh at her victory. However, unknown to her, there was an end of the road sign that she just realized. Kevin would have been mad at her if one small dent appeared on the car. However, he said he wouldn't forgive himself if anything happened to her.

She had no choice. She had to react immediately; she took a rock and morphed her body to be rock-like, and without any hesitation, dived out of the front door before she could reach the road end sign.

Although, she was safe, the car wasn't so lucky, hitting every bump on the way down. Kari saw her life flashing away as she saw the car getting worse and worse as it was nearly reaching the bottom of the hill. Each hit made Kari close her eyes. She kept them covered during the last rounds of hits.

"It isn't that bad" She opened her eyes to see the damage.

Despite being far away, she could tell that the car was beyond repair. Alien technology wouldn't have been able to repair the damage the car had taken. Crushed up squares at the garbage dumps looked better than Kevin's car. She gulped as she had crashed ships better than Kevin's car. She sighed bringing the car with her as she absorbed the metal to make sure she was strong enough to carry it home.

She had only one thought as to what Kevin will wake up to.

_Kevin is going to kill me, so much for a normal life _

**Well, I hope everyone liked that chapter. I know it was particularly hard for me to write out Kari and Kevin talking to one another. I hope everyone stays in tune when the next chapter comes along. Kari you had one job, ONE JOB. **

**Kari: What, I am sure it can be fixed**

**Me: With what? Duck tape and bubble gum, that thing is TOTALLED **

**Kari: I wouldn't talk about driving skills if I were you.**

**Me: o why not**

**Kari: People in a racing video game drive better than you**

**Me: *Deadpanned* next chapter will be available soon. **


	3. The Tennysons

**Welcome back, fans. Well I am glad no one was hurt in that car destruction. Well, maybe it's some sort of symbolism or something like that? Don't worry; Kevin will see how bad the damage is. Imagine you walking in your garage seeing the same thing. Yea, you can guess the reaction. So, this chapter will likely be fun for Kevin/Gwen fans. I hope you are happy. I haven't been watching the new Ben 10 show. Has it been getting good? Last time I watched it was during a war with some frog alien race; then, something about Albedo. That's how much I don't like the show. I tend to lose track of what it was. I love Ultimate Alien. That show is the best one in the Ben 10 series. Heck, I will go far as to say I love the first show better than Ominiverse. Sorry about that, I lost my cool for a second, rambling like a fanboy again. So, here's my feedback. **

**Kira Sema: Glad you like it. Heaven gets a cookie. *gives cookie* **

**Kari: Hey, what about my cookie**

**Me: Are we at the bottom of the page**

**Kari: fine fine, but you own me for this.**

**Me: I know, now get back there and prepare yourself for what i have in store for you. **

**Kari: Fine, but if i act too girly in this chapter, i am coming for you. **

_Disclaimer: I don't own the rights to Ben 10. Ben 10 Belongs to Cartoon Network_

Chapter 3: The Tennysons

Kari woke up at the crack of dawn. She saw her brother fast asleep. She hoped to sneak out of the room before he would discover what exactly she did to his car. However, he woke up about a good few seconds later. Kevin saw his sister sneaking out of the room. Kevin wasn't sure when she got up, but he was able to find out sooner or later.

"Hey, i hope you aren't going to use my car?" Kevin yelled. He didn't want anyone using his car. Especially, his sister. She had a bad happen of breaking his cars regardless of what form they were in. Whether they were toys, models, drawings, and even his first car. Kevin knew he was bad at cars, but she was even worst when she got behind the wheel.

Kari turned around quickly to confront her brother. "I would never think about using your car. I was just going to go by the Tennyson's house. I figured since you are good friends with them, why don't i try to bond with Gwen and Ben."

Kevin noticed something was off. She would never try to seek to bond with other people. He could see past her lies.

"Well, i think i should be going now." She rushed to the outside doors hoping that her escape would be fast enough to not hear his voice.

"Huh, okay then." Kevin yawned as he got dressed in a slow fashion. He stretched his body grabbing the second piece of toast since Kari left in such a rush. Today, he would be too busy to see Ben or Gwen. He had worked hard on his new car to even think about hanging out with them today. He even told them that he was very busy with fixing the new car.

Kevin opened the door. "Okay, how are you doing today my pretty..."

The dark haired male quickly dropped his piece of toast. He looked onto the details of how flawed his car was. From the mutilple scractches to pieces of the car falling apart. He even noticed that one of the seats was still on fire. If it was possible for jaws to drop to the ground, then Kevin's jaw would be going to the center of the Earth. He knew that this wasn't the shape he left his car in last night. He knew that Ben wasn't capable of getting into his garage. He knew that Gwen would never touch his car without permission. He only knew one person that would do this.

"KARI!" Kevin yelled from the top of his lungs.

* * *

"I can't believe you totaled his car." Ben couldn't help but laugh at the situation that Kari was in.

"Ben, i am sure Kari didn't mean to destroy his car." Gwen tried to defend Kari.

"No, i really totaled his car intentionally." Kari lied. She looked up at Gwen. She now understood why Kevin loved this girl so much. The dark haired girl smiled as she leaned back on the chair of the Tennyson household. "Do you guys have anything fun around here to do, or is it the whole chasing aliens thing."

Ben and Gwen looked at one another. They had many questions for Kari, but they felt that Kari might lie to them or be loyal to her brother on not telling the Levin Family secrets. Kari saw how they were not answering her questions. She saw Ben's car and she got up and smiled.

"Not to see how fun it is, but i have to split before my brother decides to kill me."

"We still have a ton of questions to ask you first." Gwen halted Kari.

"Fine. He loves the color green, he often likes playing the guitar, he loves wearing sneakers, he actually likes hanging around you two, he often dreams about dancing with Gwen, he loves to watch cartoon shows about kung fu, he owns a pair of nunchakus and pratices them when no one is around, He has a secret diary where he writes down his inner thoughts, He owns a teddy bear named Mr. Cuddlesworth, He often watches the nature channel, and he is too nervous to tell you about his feelings for you." Kari listed off some secret of her brothers before she made a quick get away.

As soon as she left, Kevin slammed open the door. "Kari, where are you."

Both Ben and Gwen looked at one another. "She was just here before she left us."

Kevin growled and attempted to chase after her. "Did she tell you guys anything?"

"No not really." Gwen looked away trying to deny her thoughts on what she said.

"Something about Mr. Cuddlesworth." Ben joked.

Kevin's eyes widen as he heard what Ben said. "She told you about some bear from my childhood?"

"Nope" Gwen tried to lie once more.

Kevin sank down trying to wonder what else she told his friends. He was about to die from embarrassment. He could tell from Gwen's face that she told Gwen some person things about his feelings towards her. Ben could sense that he needed to give the couple their space. "I will go hunt her down while you two sort things out.

Ben left hoping that Kari wasn't too far behind. He couldn't help but laugh at Kevin's misfortune.

* * *

Once he made it to his car, Ben sat down and started it. Ben didn't realize that Kari was sitting right next to him. Before the teen could react, Kari swiftly put her hand on the dashboard. The hand quickly disappeared, but Ben felt the seatbelt was gripping him hard. Ben could barely talk, but it wasn't a grip of death. Kari smirked.

"I now can control this car to do whatever i want it to do. Now, i know that you are probably going to tell my brother where i am. I want to at least have some fun in this city, first. What i want you to do is drive us around. Don't leave any details of how much fun this place could be. I am dying for some action at the moment. So, either you take us to fight some aliens, or i send a lovely little picture to whatever girl you are dating and convince her that you are two-timing her." Kari smirked before setting up her phone to take a picture of them. She was blackmailing him to have some leverage over the hero.

"Okay, fine." Ben softly spoke. Soon, he found himself being released from his grip. Kari's hand returned to normal as she settled into the passengers seat. "...And i don't have a girlfriend by the way."

"Well, that's nice." Kari couldn't care less. She didn't want to be coped up in the Levin home. She was bored out of her mind seeing her stepdad and hearing him talk would make her want to rip her ears out. Kari snapped back seeing Ben was starting the car and preparing to drive them to wherever she desired.

She could tell that he was a flirty hero. "Listen up, Hero." She announced.

"Just because we are alone together, doesn't mean i am going to let you kiss me or any of that mushy stuff. Kevin will even kill you if you try to make a move on me. Besides, i already have a boyfriend." Kari told Ben. She was lying about the whole 'boyfriend thing'. She would hope there would be a guy in town that was tough enough to win her heart. She did have one guy in mind. He was the hero that saved the world from the DNAliens. Ever sense she heard about him on the radio, she had been smitten with the guy and hopes that he was in town. She wants to tell that hero that he inspired her to do super hero work. The guy might have been super bluff, with long floating hair, a six pack chest, and even other qualities about him that she would melt over. She shook her head seeing him watching her.

"Just keep driving, Tennyson." Kari complained as she crossed her arms. She soon cuddles on the seat. She closed her eyes and kept her foot on the dashboard. She was prepared just in case Ben would betray her to her brother. Ben drove off hoping that whatever danger lied ahead was only minor and wouldn't give Kari such a hard time.

* * *

**Well that seemed like a very good chapter to tell, I wonder how people feel between Kari and Ben. Don't worry, Kari is my OC and she will not fall in love that easily. **

**Kari: What makes you so sure? **

**Me: Well, I know you aren't going to lay down for a guy that easily**

**Kari: You are right about that **

**Me: Yea, I don't like it when people magically fall in love at first sight. It's a thing that has been overused thousands and thousands of times. **

**Kari: and you like the type of love that happens over a long period of time. **

**Me: That's how it works in real life. Not this 'O I just met you and I love you already' BS. **

**Kari: So, is that why you have trust issues with people **

**Me: It's not like that I mean it's just that….**

**Kari: You got nothing on me**

**Me: Anymore complaining out of you missy and I will make you and Ben kiss in the next chapter. **

**Kari: alright alright, Hey where's my cookie **

**Me: I am going to give you something better than a cookie *Gives Kari a brownie* **

**Kari: YAAAAAAA *eats the brownie***

**Me: I can't wait until next chapter, you will get to meet your mystery lover. **

**Kari: You mean the guy i love so much. I finally get to learn who my mysterious man is that i love so much. **

**Me: Yeah, the guy who saved the world from the DNAliens. **

**Kari: I can't wait to meet him. I wonder what he will be like. I only hope that Ben isn't around for me to tell the hero how much i love him. Ben will be so crushed to learn how sexy my hero will be. He even is wearing the ****ultimatrix to defend the world. With me as his wife, nothing will stop us. **

**Me: *laughs* **

**Kari: What's so funny. **

**Me: *Tries to contain the laughter* Nothing, just wait until the next chapter. **

**Me: Until then, see you all later**


End file.
